A buffered bike lane provides a more protected and comfortable space for cyclists than a conventional bike lane. A painted buffered bike lane can also serve to help faster moving cyclists safely pass slower moving cyclists on busy, well-cycled stretches of road.

Examples of how buffered bike lanes have helped riders in San Francisco:
http://www.sfbike.org/main/one-more-link-is-luxurious-for-this-classical-singer/
http://www.sfbike.org/main/one-more-link-a-separated-bike-lane-improving-division-street/

Chicago recently installed a buffered bike lane that also instantly improved conditions for cyclists:

http://vimeo.com/moogaloop.swf?clip_id=32986515

The section of Highway 101 between La Costa and Leucadia is a 40 mph road and a buffered bicycle lane will allow more cyclists to start riding.